1. Field of the Invention
The invention relates to a process for preparing bis(3-t-butyl-4-hydroxyphenyl-2,4-di-t-butylphenyl)resorcinol diphosphate.
2. Description of Related Art
Bis(3-t-butyl-4-hydroxyphenyl-2,4-di-t-butylphenyl)resorcinol diphosphate(HDP) is considered as a homologous compound in the production process thereof, which has a following structure: ##STR1## HDP is a flame retardant of aromatic phosphorous series and is suitable for bonding with monomers such as, for example, monomers of epoxy resin. The product obtained after polymerizing can retain their physical and chemical properties as well as their weathering resistance that makes them being an environment friendly product in the future.
Processes for synthesizing hydroxy-reactive flame retardant of aromatic phosphorous series, such as those described in U.S. Pat. No. 5,506,313 (1996) and U.S. Pat. No. 5,278,212 (1994), provided a product as a mixture having a low proportion of the main component, and did not disclose the manner of purification or washing of products with aqueous solution of hydrochloric acid. The main disclosure thereof comprised of demonstrating the slowing of the physical and chemical changes after reaction of the hydroxy aromatic phosphorous-based flame retardant
Objects of the present invention are, therefore, intended to increase the purity of a single product, to improve the reproducibility of the reaction and to simplify the reaction steps so as to provide the feasibility of mass production
The above-described objects can be accomplished by a process for preparing bis(3-t-butyl-4-hydroxyphenyl-2,4-di-t-butylphenyl)-resorcinol diphosphate according to the invention.